Cannon BJC3000 Cartridge problem

The problem: The black ink does not print. The other colors do. The cartridge is a BJC color cartridge that holds three colors plus black. The ink "tank" has ink and does feed.
I think the Nozzle in the cartridge is plugged. Running the print head cleaning utility does not clear the nozzle. I am thinking of removing the ink tanks and immerse the head in alcohol and let it soak. Do you think that would clear the nozzle? What about the possibility the alcohol would ruin the cartridge? Has anyone solved this problem and if so how? Thank you for any help you can provide.